This article is an overview of scanning acoustic microscopy, which is one of the more advanced ultrasonic imaging technologies. The scanning acoustic microscope (SAM) uses ultrasound to produce enlarged images of the microscopic structures of materials. In other words, the SAM is an instrument that subjects an object to ultrasound and detects the variations of the elastic properties of the object. The elastic properties are determined by the molecular arrangement of the material, molecule size, intermolecular force or the like, and each material has its unique characteristics. Accordingly, each object reacts in its own peculiar way when subjected to ultrasonic waves. The waves received from the object can be converted into an image. Because ultrasonic waves can penetrate into an object's interior, the surface and also the interior can be visualized.
The contents of this article are as follows: First, the need in industry for this process is described. Second, the history of the development of the SAM is illustrated in brief. Third, the basic theory of ultrasonic imaging used in the SAM is depicted, as well as the basic theory of the implements used in the SAM. Furthermore, the
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) curve method for material characterization is described. Selected images are given for a better understanding of the sections.